Objective: Motor cortex stimulation (MCS) has been used for over 30 years to treat refractory chronic neuropathic pain. However, its efficacy remains controversial, its mechanisms of action unclear and the optimal electrode placement is debated[1]. Our aim was to analyze a large series of patients to identify optimal lead localization. Methods: We analyzed retrospectively 98 patients treated with MCS for chronic neuropathic refractory pain across eight French, German and Brazilian centers. Postoperative CTs were normalized in the MNI template using ANTs to calculate the coordinates of the active contacts. These coordinates were mapped onto several MNI space-registered atlases[2,3]. The electrode-pial distance was computed. Patients were categorized in non-responders (NR - all stimulation settings failed to relieve the pain) and responders (R). The latter were divided into certain-responders (CR - the analgesic effect stopped when the IPG was turned off) and probable-responders (PR). Logistic regression was used to compare patient characteristics, stimulation parameters, electrode coordinates and atlas values. Results: Statistical tests revealed a significantly greater electrode-pial distance in NR vs. R (5.73 vs 4.94mm, p<.022). The stimulation frequency and intensity were lower in R. Leads located inferiorly and on the right hemisphere were associated with higher response rates. While effective electrodes were often localized on the premotor histo-functional areas, the difference was not significant. Electrodes were effective regardless of motor cortex somatotopy. Pain relief was associated with stimulation of 90-100mm long streamlines. Conclusion: These results challenge traditional MCS assumptions. Precise targeting of somatotopic motor regions may not be critical for pain relief. Instead, duro-pial distance could predict MCS response. The association with medium length streamlines suggests MCS modulates distant pain centers. This study highlights the need for a more nuanced approach to MCS, moving away from motor somatotopy and integrating connectivity analyses to refine electrode placement and optimize clinical outcomes. 1. Lefaucheur, J.-P. Cortical neurostimulation for neuropathic pain: state of the art and perspectives. Pain (2016). 2. Glasser, M. F. et al. A multi-modal parcellation of human cerebral cortex. Nature (2016). 3. Bajada, C. J. Fiber length profiling: A novel approach to structural brain organization. NeuroImage (2019). Fig. 1 Lead localization in face(green), upper_limb(red) and lower_limb(blue) in responders Fig. 2 A.Odds Ratio of response as a function of fiber length distribution B.Effective(red) and ineffective(blue) leads on short fibers (first row) and medium fibers (second row) pial surfaces in responders

Background: Trigeminal neuralgia (TN) consists of unilateral paroxysmal attacks of facial pain triggered by touch, speech or eating. It is usually caused by a neurovascular conflict and is often treated with microvascular decompression or ablative procedures. In some patients, TN is secondary to a brainstem lesion that can be isolated or in the setting of multiple sclerosis. In such cases, pain tends to be more refractory to conventional therapies, presumably because the pain generator is located proximal to the nerve which all interventions target. We are currently conducting a phase 1 trial of a new treatment paradigm: deep brain stimulation (DBS) of the trigeminal tract proximal to the pontine lesion (NCT05451251). Objective: Assess the impact of trigeminal tract stimulation on facial sensory thresholds. Methods: We report the results of the first patient enrolled in our DBS-TN trial, a 68-year-old male with TN secondary to a solitary pontine lesion who had 2 microvascular decompressions and 4 ablative procedures. A posterior fossa trajectory was used to implant a DBS electrode within the trigeminal tract proximal to his pontine lesion. Quantitative Sensory Testing (QST) performed per the German Research Network on Neuropathic Pain protocol was conducted preoperatively, postoperatively, and while stimulating the trigeminal tract at 130 Hz and 1200 Hz using an external stimulator connected to an externalized lead extension. Sensory thresholds for the mandibular branch affected by TN were compared between all conditions using a two-tailed paired t-test. Results: Lead insertion into the trigeminal tract did not produce facial numbness or related side effects. Stimulation at 130 Hz produced facial hypoesthesia with statistically significant changes in the thresholds for cold detection, cold-induced pain, warm detection, heat-induced pain, thermal sensory limens, mechanical pain sensitivity, mechanical detection, and wind-up ratio. Stimulation at 1200 Hz produced less profound changes, but also altered thresholds for warm detection, mechanical detection, mechanical pain, mechanical pain sensitivity, and wind-up ratio. These alterations occurred only during stimulation and resolved upon its interruption, demonstrating stimulation-induced and frequency-dependent modulation of thermal and mechanical sensory thresholds. Conclusion: DBS of the trigeminal tract can modulate facial sensory thresholds in a patient with TN secondary to a solitary pontine lesion and produce reversible facial hypoesthesia. This feature could potentially be used to interrupt triggers that generate pain attacks and abort attacks once they occur. Our trial is ongoing to confirm these findings over the long term and in a larger cohort of patients.

Background: Chronic neuropathic pain affects nearly 20% of adults, profoundly diminishing quality of life and contributing to chronic disability, depression, and anxiety. Conventional deep brain stimulation (DBS) targets, such as the ventrocaudal thalamus (Vc; VPL/VPM) and periaqueductal/periventricular gray (PAG/PVG), focus on sensory-discriminative circuits but provide sustained relief in only about one-third of patients. These approaches frequently overlook the affective and cognitive dimensions of pain (e.g., rumination, catastrophizing), which amplify suffering and drive opioid dependence. Moreover, fixed open-loop DBS cannot adapt to dynamic pain states, leading to habituation and reduced long-term efficacy. An unmet need exists for adaptive, closed-loop neuromodulation that integrates individualized targeting with intracranial biomarker detection to dynamically modulate various dimensions of pain. To address this gap, we present a case report and a stereoelectroencephalography (SEEG)–driven protocol for individualized DBS target selection. Methods: A 74-year-old woman with a 12-year history of severe atypical right facial neuropathic pain (VAS 10/10), refractory to pharmacotherapy, nerve blocks, microvascular decompression, and Gamma Knife radiosurgery, underwent SEEG. Thirteen depth electrodes targeted sensory (Vc), affective (anterior insula [AINS], anterior cingulate cortex), cognitive-limbic (orbitofrontal cortex, ventral striatum/anterior limb of internal capsule [VS/ALIC]), and reward-related (ventral tegmental area) regions. Over 10 days, the patient underwent 134 randomized, blinded trials of bipolar stimulation at low and high frequencies with interspersed washout periods. Patient-reported outcomes included VAS, McGill Pain Questionnaire affective subscore (MPQ), and Pain Catastrophizing Scale (PCS). Clinical responses, SEEG biomarkers, and tractography guided final DBS target selection. Results: Stimulation of conventional sensory targets (VPM, PVG) provided minimal analgesia (<10% VAS reduction). In contrast, stimulation of affective targets resulted in subtantial pain relief: continuous AINS stimulation reduced VAS from 10 to 5, and VS/ALIC stimulation reduced VAS scores from 10 to between 2–4. These findings were confirmed in double-blind sham-controlled trials. Subsequently, permanent bilateral DBS electrodes (Medtronic Percept, SenSight leads; 4 leads, 2 IPGs) were implanted in AINS and VS/ALIC. At two-month follow-up, ongoing clinical programming reduced average VAS scores to approximately 4–5/10, alleviating subjective affective distress and enhancing functional capacity. Conclusion: This case highlights the necessity and effectiveness of addressing affective and cognitive dimensions in refractory neuropathic pain through individualized neuromodulation strategies. SEEG-guided parameter testing identified non-traditional DBS targets (bilateral VS/ALIC and AINS) that provided substantial symptomatic relief compared to classical sensory targets. Incorporating intracranial biomarker-informed mapping into DBS decision-making can overcome limitations of generalized approaches, supporting personalized management of complex chronic pain syndromes.

Background: Deep Brain Stimulation (DBS) of the anterior cingulum has been recently proposed to treat refractory chronic pain but its safety and its efficacy have not been evaluated in controlled conditions. Our objective was to evaluate the respective feasibility and safety of sensory thalamus (Thal-DBS) combined with anterior cingulate (ACC-DBS) DBS in patients suffering from chronic neuropathic pain. Methods: We conducted a bicentric study (clinicaltrials.gov NCT03399942) in patients suffering from medically-refractory chronic unilateral neuropathic pain surgically implanted with both unilateral Thal-DBS and bilateral ACC-DBS, to evaluate successively: Thal-DBS only; combined Thal-DBS and ACC-DBS; ACC-DBS “on” and “off” stimulation periods in randomized cross-over double-blinded conditions; and a 1-year open phase. Safety and efficacy were evaluated by repeated neurological examination, psychiatric assessment, comprehensive assessment of cognitive and affective functioning. Changes on pain intensity (Visual Analogic Scale) and quality of life (EQ-5D scale) were used to evaluate DBS efficacy. Results: All the patients (2 women, 6 men, mean age 52,1) completed the study. Adverse events were: epileptic seizure (2), transient motor or attention (2), persistent gait disturbances (1), sleep disturbances (1). No patient displayed significant cognitive or affective change. Compared to baseline, the quality of life (EQ-5D utility score) was significantly improved during the ACC-DBS “On” stimulation period (p=0,039) and at the end of the study (p=0,034). Conclusion: This pilot study confirmed the safety of anterior cingulate DBS alone or in combination with thalamic stimulation and suggested that it might improve quality of life of patients with chronic refractory neuropathic pain.

Objective To describe the technique and first results of high cervical spinal cord stimulation (hcSCS) with high frequency (10 kHz) as treatment in drug-resistant neuropathic facial pain Materials and Methods As an off-label treatment, 12 individuals (5 male/7 female) with trigeminal neuropathy had hcSCS electrode placement (with tip C1/2) mainly in general anesthesia, only 4 cases in local anesthesia. After successful test stimulation with an external impulse generator (IPG), 8 patients received a rechargeable internalized pectoral or abdominal IPG. The tunneling of the electrode cable to the IPG implantation site was done under general anesthesia. The follow up period was at least 4 month. Results In all but one patient with a cervical stenosis and need for a microsurgical placement, the implantation of the epidural electrodes were achieved without any technical problem via upper thoracic interlaminar window using a Touhy canula . There was one intermittent neurological deterioration in a patient with multiple sclerosis (temporary hand numbness). No surgical site infection occurred. 8 of the 12 patients had a relief of their facial pain of at least 50%. In the 4 cases without pain amelioration, the electrodes were removed in local anesthesia. Conclusions The hcSCS procedure may be a treatment option in desperate cases of therapy resistant trigeminal neuropathy for it seems feasible and safe. It is an off label use. Clinical studies should be conducted in more patients and with long term follow up.

Background: Chronic neuropathic pain is a symptom associated with high individual and social burden. Treatment of these patients can be complex with several conservative and invasive therapy options. Thalamic deep brain stimulation can be a last resort treatment option for patients with chronic neuropathic pain, if no other therapy has been proven to be effective. There is a considerable variability within different centres regarding targeted structures, the most common being the ventral posteromedial nucleus and ventral posterolateral nucleus (Vpm/Vpl). This study aims to analyse preoperative tractography in combination with fMRI results as potential planning tools for individualized targeting. Methods: Five patients with chronic neuropathic pain could be included in this study with diverse peripheral or central lesions. All patients received preoperative fMRI imaging to identify the secondary somatosensory cortex (S2). Subsequently, stereotactic surgery was performed to implant unilateral DBS electrodes targeting Vpm/Vpl. Clinical outcome was measured using the visual analogue scale (VAS), all patients had regular follow-up visits up to 30 months postoperatively. The electrodes and the active contacts were reconstructed using leadDBS. We simulated the activated tissue surrounding the electrodes (VTA) at different follow-up time points. Probabilistic tractography was performed to identified the tracts connecting M1, S1 and S2 to Vpm/Vpl. Finally, we calculated the overlap between each VTA and the identified tracts, and correlated the results to the clinical outcome of each patient. Results: Three out of five patients were classified as responders, demonstrating a reduction in pain intensity of more than 50% on the VAS under chronic thalamic stimulation in the Vpm/Vpl. No complications were reported during the follow-up period. In the cohort of five patients there was no consistent activation pattern in fMRI as response to the sensory task and all BOLD responses were shifted relative to the expected S2 area. Structural connectivity could be demonstrated between the primary motor (M1), the primary somatosensory (S1) and the secondary somatosensory (S2) cortex as well as the functional areas exhibited during fMRI to the Vpm/Vpl with no clear correlation to the clinical outcome. Conclusions: DBS was well tolerated in this cohort, with no procedure-related complications. Based on this small cohort, thalamic DBS could be a potentially safe and in some cases possibly effective method to treat chronic, therapy-refractory neuropathic pain. Extensive variability of activation patterns in the fMRI during sensory task could indicate functional neuroplastic changes, which could also complicate the interpretation of structural connectivity.

Background: Chronic refractory neuropathic pain imposes a heavy clinical burden, yet conventional deep brain stimulation (DBS) protocols concentrate on sensory-discriminative circuits and neglect cross-diagnostic affective and cognitive aspects of pain. Adaptive, closed-loop DBS, where stimulation parameters adjust in real time based on neural biomarkers offers a multidimensional, state-dependent modulation paradigm, which may overcome the limitations of fixed, open-loop systems. Here, we demonstrate in an N-of-1 study how acute stereoelectroencephalography (SEEG) can identify pain-state–specific electrophysiological signatures and guide affective-target selection for chronic, closed-loop DBS. Methods: A 74-year-old woman with intractable facial neuropathic pain (VAS 10/10), unresponsive to medications, nerve blocks, and surgical interventions, underwent a 10-day inpatient SEEG trial. Thirteen depth electrodes were stereotactically placed in sensory (ventral posteromedial [VPM] thalamus), affective (anterior insula [AINS], ventral striatum/anterior limb of internal capsule [VS/ALIC], centromedian-parafascicular nucleus), cognitive (orbitofrontal cortex), and reward-related (ventral tegmental area [VTA]) regions. Continuous local field potentials (LFPs) were recorded alongside 264 patient-reported assessments: McGill Pain Questionnaire affective subscore (MPQ), Pain Catastrophizing Scale (PCS), and Visual Analog Scale (VAS). Natural pain fluctuations, 134 randomized bipolar stimulation trials (low vs. high frequency), and double-blind sham runs were interleaved with washout intervals. Electrophysiological features, including spectral power (delta to high-gamma), coherence, and phase-amplitude coupling, were extracted. Semi-supervised k-means clustering categorized high- versus low-pain states, and logistic regression models predicted binarized affective thresholds, quantified by area under the ROC curve (AUC) and odds ratios (OR). Results: Despite persistently elevated VAS scores (mean 9.6 ± 1.5) failing to track subjective fluctuations, MPQ and PCS scores exhibited dynamic variability correlating with distinct LFP biomarkers. Delta and theta band power in AINS and VS/ALIC were associated with heightened affective pain. High-gamma activity in AINS was also linked to pain-state transitions. An optimized logistic model classified pain states with high accuracy. Phase-amplitude coupling and network connectivity analyses elucidated dynamic interactions between affective and sensory circuits. Sequential stimulation mapping confirmed significant analgesia at VS/ALIC (VAS 10→2) and AINS (VAS 10→5), whereas VTA stimulation aggravated pain. Conclusion: Acute SEEG monitoring identified precise electrophysiological biomarkers of affective pain, facilitating informed target selection with potential for chronic closed-loop DBS. The anterior insula and VS/ALIC emerged as optimal loci for modulating affective pain dimensions. These findings provide a framework for biomarker-guided, adaptive neuromodulation strategies tailored to individual pain profiles, representing a significant advance in treating refractory neuropathic pain.

Background: Parkinson's disease is the second most common neurodegenerative disorder worldwide after Alzheimer's dementia. In Germany, approximately 400,000 people are affected. Back pain and spinal deformities are common comorbidities in patients with Parkinson's disease. Deep brain stimulation (DBS) is well established as a core component in the treatment of Parkinson's disease concerning the neurological cardinal symptoms. However, the value of DBS as a treatment option for chronic back pain and spinal deformities in Parkinson's disease is unclear, except for a few reports. The research question of the present study is the effect of DBS on back pain and spinal deformities associated with Parkinson's disease. Methods: In a prospective observational study, the Oswestry Disability Index (ODI) was used to quantify back pain in 52 Parkinson's patients treated with DBS, one week pre-operatively and twelve months post-operatively. Additionally, biplanar full-body X-rays were taken to assess the sagittal balance. Positive approvals from the responsible ethics committee and the Federal Office for Radiation Protection have been obtained. Results: Of the patients studied, 42% reported a pre-operative ODI > 20%, indicating at least moderate disability due to back pain. The median ODI in this patient group was 36%. One year after the intervention, the median ODI in this patient group was 27%, indicating a clinically significant improvement (p=0.003). A deviation in sagittal vertical axis (SVA) was diagnosed pre-operatively in 50% of the patients. Of these patients, 42% exhibited normal SVA one year post-operatively. Conclusions: This study is the first to examine the effect of DBS on Parkinson's-associated chronic back pain and adult spinal deformities in a large sample of patients with Parkinson's disease. DBS appears to be a promising therapeutic approach in treating these comorbidities of Parkinson's disease. However, the pathophysiology of Parkinson's-associated back pain remains unclear and should be investigated in subsequent exploratory studies.

Objective: Our aim was to assess the effectiveness and migration rate of occipital nerve stimulation (ONS) utilizing a newly developed anchoring lead (ANKERSTIM™, Medtronic) in patients treated by ONS for refractory chronic cluster headache (rCCH). Methods: We included 38 rCCH patients (16 women, mean age 43 years) in a prospective multicenter ONS registry from 2019 to 2023, including 33 patients implanted with the ANKERSTIM™ leads and 5 with other leads. The effectiveness of ONS was evaluated by the frequency of CCH attacks, abortive and preventive medication use, quality of life (EuroQol 5 Dimensions scale), the functional (Headache Impact Test-6) and emotional (Hospital Anxiety and Depression Scale) impacts. Complications were monitored, focusing on electrode migration, device malfunction, infections, and local pain. Results: After a mean follow-up of 20.3 months post-ONS, patients with Ankerstim implants reported a 66.6% reduction in attack frequency (P = 0.0022) and a significant improvement in their quality of life. During the follow-up period, 11 patients in the ANKERSTIM™ group experienced device-related complications, including infection (6.1%), lead migration (6.1%), hardware dysfunction (12.1%), and pain at the lead insertion site (12.1%). The migration rate was 40% in the patients implanted with other electrodes. Conclusion: ONS using ANKERSTIM™ leads showed comparable efficacy, while also presenting a lower risk of migration, compared to ONS using other leads reported in our study and previous studies

Context. Neuropathic facial pain (NFP) that remains refractory to optimal pharmacological management poses a significant burden on patients and a challenge to pain specialists. Recent clinical evidence indicates that peripheral nerve stimulation (PNS) exhibits therapeutic potential in managing occipital and facial neuropathic pain. This study aims to evaluate the effectiveness of occipital nerve stimulation (ONS) specifically in the treatment of NFP. Methods. We conducted a retrospective analysis of prospectively enrolled patients with refractory NFP unresponsive to optimal specific medical therapy and, in some instances, motor cortex stimulation. These patients were treated under a compassionate use framework for unilateral NFP using ONS. Each patient underwent an initial ONS trial lasting a minimum of two weeks. If they experienced an improvement in their NFP exceeding 40%, they proceeded to definitive implantation one month later. Results. 13 patients were included in the study, with a mean age of 66 years and a male-to-female ratio of 1.2:1. The average duration from NFP onset to ONS surgery was 9.6 years. During the trial period, only 6 patients (46%) experienced significant improvement and proceeded to implantation. However, 3 of these patients (23%) did not report any benefit one-month post-implantation, motivating hardware removal. Additionally, in 2 patients (15%), the initial improvement did not translate into long-term relief. Ultimately, only 1 patient (8%) reported sustained long-term improvement in NFP. Notably, this patient had previously experienced a 10-year benefit from motor cortex stimulation prior to undergoing ONS. Conclusion. In light of our results, the limited and inconsistent improvements observed in a minority of patients suggest that ONS may not be a reliable surgical treatment option for neuropathic facial pain.

INTRODUCTION Spinal cord stimulation (SCS) is an evidence-based therapeutic modality for chronic pain syndromes that do not respond to conservative therapy. One of the most common surgical indications is failed back surgery syndrome (FBSS). OBJECTIVES We performed a long-term follow-up of patients operated for FBSS with spinal cord stimulation, separately investigating changes in lower extremity and axial pain, as well as their quality of life before and after surgery. MATERIAL AND METHOD Spinal cord stimulation was used to treat 158 patients with chronic pain between 2003 and 2024. The spinal pain syndromes were FBSS (n=64) and degenerative scoliosis (n=10). Patients who had undergone surgery an average of 6.1 (±3.4) years prior were selected for long-term follow-up (FBSS: n=16, degenerative scoliosis: n=4, total 20 patients, mean age: 66.4 years, range 43-82 years, female:male=16:4). Face-to-face and telephone assessments were performed preoperatively and at the final follow-up with the following tests: pain intensity was analysed with the Visual Analogue Scale and quality of life with the Oswestry Disability Questionnaire. Lower limb and axial pain were assessed separately. RESULTS Of 61 patients with chronic spinal pain syndrome, 20 were eligible for long-term (6-year) follow-up. Visual Analogue Scale scores and Oswestry Disability Index values demonstrated significant improvement in both lower extremity and low back pain, as well as in quality of life, compared to preoperative data (p<0.05). Lower extremity pain improved from 9.6 preoperatively to 2.4 immediately postoperatively and 3.4 after 6 years of long-term follow-up according to VAS. Axial VAS scores improved from 9.2 preoperatively to 3.9 immediately postoperatively and 4.8 after long-term follow-up. ODI improved from 86% preoperatively, to 34% immediately postoperatively, to 43% after long-term follow-up. CONCLUSIONS Our results suggest that spinal cord stimulation can be successfully used in the long term for the relief of lower extremity and axial pain of FBSS and degenerative scoliosis origin. Consistent with previous findings in the literature, our patients showed a more significant improvement in lower extremity pain than axial pain.

There is little literature about the management of patients that have or undergo immunosuppression due to other conditions like cancer, various types of treatments, or severe rheumatological disease. These patients usually take immunosuppressive drugs or undergo treatments like chemotherapy or radiation, that modulate the immunological capability of preventing infections post implantation. These are usually patients that require pain pumps or neurostimulators. We present our protocol that includes preparation of the patient with skin, urinary, rectal, nasal and blood cultures. Assessment of white blood cell count and the use of immuno stimulating drugs prior to the procedure, according to the directions of the attending oncologist or other physician and with the contribution of a haematologist, we prepare these patients monitoring their lab work for at least a week. During the procedure meticulous skin preparation especially at the area of the pocket is made and in every incision Vancomycin powder is applied. Sutures are removed at least 15 days post procedural and anti microbial drugs are administered for at least 15 days. Special care is taken, when there are ongoing treatments like chemotherapy or immunosuppressive drugs, in order to arrange the procedure at least a week after the last immunosuppressive treatment. With this protocol, we have implanted 11 pumps and 6 neurostimulators, with only one post procedural infection. We think that following such a protocol can provide safer conditions for applying neuromodulating devices for the treatment of pain in this particular patient category. In such patients of course large cohort studies are required to establish long-term safety.

INTRODUCTION Degenerative scoliosis, which is not relieved by conservative treatment, is mainly treated by direct spinal surgery. However, conventional direct spinal surgery under general anesthesia may be associated with an increased risk of morbidity and increased surgical complications. The relatively minimally invasive spinal cord stimulation analgesia method, which can be performed under local anesthesia, percutaneously and with less surgical stress, may offer an alternative and long-term analgesic therapy in such cases. MATERIAL AND METHOD In our institute, we planned direct spinal surgery for six patients with degenerative scoliosis suffering from intolerable back pain and lower limb pain. However, the presence of polymorbidity, we chose the lower risk spinal cord stimulation surgery as the first therapeutic option (10 women, mean age 69 ± 11 years). Patients completed a self-administered test battery before and after surgery (Oswestry Disability Questionnaire - ODI, Visual Analogue Scale - VAS; measuring back and lower limb pain separately). Questions on analgesic intake habits and satisfaction with therapeutic effect were also assessed. Average follow-up was 5,1±1,6 years. RESULTS ODI decreased from preoperative average of 88 ± 8% to 37 ± 14% postoperatively, VAS (back) from 87 ± 16 mm to 47 ± 15 mm, VAS (lower limb) from 90 ± 17 mm to 7 ± 16 mm separately. Fifty percentage of patients did not require analgesic medication after stimulation, while the other 50% had reduced medication. All patients were satisfied with the results of spinal cord stimulation. CONCLUSIONS Our results show that spinal cord stimulation resulted in significant improvements in quality of life (ODI) and pain reductions in during the 5 years follow-up. In our opinion, spinal cord stimulation is an alternative to direct spinal surgery for the relief of back and lower extremity pain caused by degenerative scoliosis in polymorbid patients at high surgical risk.

Abstract Background and Objectives: Percutaneous cervical cordotomy (PCC) is used to provide pain palliation to oncological patients suffering from unilateral intractable cancer-related pain below the C4 dermatome. We present our experience utilizing O-arm intraoperative imaging for PCC in a large cohort of patients. Methods: A retrospective analysis was conducted of all patients who underwent PCC between March 2016 and April 2025 at our institution. Data were collected for up to 12 months after the procedure, including demographic and clinical information. The difference in pain before and after the procedure was calculated using the visual analog scale (VAS) score. Results: A total of 114 patients (62 males) underwent 120 PCC procedures. The average age of patients was 62.9 (range 22-88, median 65, SD ± 12.5) years. Most cases (86%) were performed in an awake state or under minimal sedation, while 15 cases (14%) were performed under deep sedation or general anesthesia using intraoperative monitoring (IOM). In 95% of cases (114 out of 120), there was a significant reduction in pain immediately following the procedure with an average score decreased by an average of 8.5 points (from 9.3 points before the operation to 0.8 points postoperatively). In only 1 case, an immediate failure was observed, with no pain relief following surgery. Five patients experienced only mild to moderate postoperative improvement. The median hospitalization time was 2 days. The average survival time was 4.6 months (ranging from 0.9 to 46.97, with a median of 2.9 months). Only eight patients survived beyond the first year. At one month post-operative, 79 patients were available for follow-up, and 72% of them (57 patients) reported complete pain relief. Three months postoperatively, 31 patients were available for follow-up, and 61% (19 patients) reported complete pain relief. Six months postoperatively, 13 patients were available for follow-up, and 85% (11 patients) reported complete pain relief. Three patients (2.5%) developed ipsilateral hemiparesis; two of them improved spontaneously within one month of rehabilitation, nearly regaining their baseline function. The most common complication was mirror pain, which developed in 34 cases (28%). Nineteen cases were rated as mild were well-managed with pain relievers; fifteen cases were rated as severe. Conclusion: PCC is safe and effective in managing intractable oncological pain; however, the average survival time after PCC is typically only several months, indicating a lack of awareness of the procedure among pain specialists and late referrals. We suggest that PCC should be considered earlier in the course of treatment of cancer patients suffering from pain that is refractory to medications.

Background : The radiofrequency unilateral interruption of the spinothalamic tract at the level of the superior colliculi in the mesencephalon is one of the more ancient functional neurosurgery operation. Based on the literature review our aim is to consider the potential role of this old intervention in the modern neurosurgical armamentarium against cancer pain taking into account the evolution of the operative technique and the emergence of alternative approaches. Material and Method : We reviewed the literature in order to analyse the anatomical targeting of the spinothalamic tract, the technical strategies, the efficacy on pain, the morbi-mortality the comparison of the safety efficacy ratio with other surgical technics depending on the indications. Among 19 published series only 4 are reporting only cancer pain patients. Two of these 4 series are reporting an anterior approach. Results : At the level of the superior colliculi the spinothalamic tract location is quite stable. With the anterior approach, a trajectory parallel to the quadrigeminal plate and a target at 7-8 mm from the midline the rate of permanent oculomotor palsy is very low. In patients operated under local anaesthesia with electrical stimulation of the target area painful paraesthesia due to injury of the medial lemniscus are very rare (min 0 max 6%). The rate of patient with analgesia of the painful area pain relive and stop and stop of pain-drug in these conditions is around 80% (min 75%-max 86%) in cancer patients. Early pain recurrences appearing within a month are due to insufficient coagulation. When morphine pump is not an option this intervention can transform the comfort of the last days of patients with unilateral drug-resistant pain of the upper part of the body. Conclusion : Although very ancient the Stereotactic Spinothalamic Mesencephalic Tractotomy (SSMT) by radiofrequency (RF) is turning out to offer a very good safety efficacy for lateralized cancer pain at the upper part of the body in drug-resistant patients with a modest life expectancy. We recommend the young generation of neurosurgeon involved in pain surgery to learn this remarkably effective intervention.

Biological Effective Dose (BED)-based planning has emerged as a promising method for predicting tissue response in high-precision radiosurgical treatments. Given that dose rate significantly influences tissue responses, the condition of radiation sources at treatment should be considered alongside patient-specific factors for individualized therapy. Additionally, BED can aid in developing optimized treatment protocols to enhance patient outcomes. To investigate factors influencing treatment outcomes, a cohort of 191 patients diagnosed with idiopathic, type 1 trigeminal neuralgia (TN) receiving first-line stereotactic radiosurgery (SRS) was analysed. All treatment plans targeted the trigeminal nerve in the prepontine cistern with a maximum dose of 80 Gy delivered at the 100% isodose using different GammaKnife units over time. Follow-up data were retrospectively collected from a prospectively maintained database. Median follow-up was 46 months (range: 12–266 months). Pain relief was achieved in 90.1% (n = 172) of patients. Of those, 172 patients, 51.2% (n = 88) experienced relapse. Kaplan-Meier analysis estimated median relapse-free duration as 73 months, with 32.1% of patients remaining relapse-free at 10 years. Medication status was documented for 186 patients, with 38.7% (n = 72) discontinuing medication completely, and another 36.6% (n = 68) reducing dosage by their latest follow-up. Univariate Cox regression showed that each millimetre increase in shot distance from the root entry zone (REZ) increased relapse hazard by 16.3% (95% CI: 2.4%–32.2%, p = 0.020), while each 10% increase in BED delivered to the REZ decreased relapse hazard by 4% (95% CI: 1.4%–6.4%, p = 0.003). Univariate logistic regression indicated each additional millimetre distal to the REZ reduced odds of medication-free status by 21.5% (95% CI: 2%–37.2%, p = 0.032). Multivariate logistic regression demonstrated maximum BED applied to the nerve positively predicted new numbness (p = 0.046), adjusted for pre-treatment pain duration (p = 0.016), beam blocking status (p = 0.960), and patient age (p = 0.053). Despite identical maximum physical doses administered, differences in maximum BED successfully predicted the risk of new numbness, highlighting the superiority of BED over physical dose in predicting tissue response. Increasing BED to the REZ improves pain control, whereas higher maximum nerve BED increases the risk of, even though it is generally well-tolerated, facial numbness. Optimizing REZ dose while minimizing the maximum BED to the nerve may enhance clinical outcomes.

Introduction Trigeminal Neuralgia (TN) is a condition causing acute attacks of pain over the areas of distribution of trigeminal branches. Gamma Knife radiosurgery (GKRS) is a mainstay of the treatment algorithm, and its efficacy and safety have been widely shown. However, a non-negligible number of patients may experience recurrence of pain after initial relief. Data on radiosurgical retreatments are still limited, and factors that may influence response to treatment and adverse effects are not well described. Methods We retrospectively reviewed patients who were retreated at our institution with GKRS for recurrent TN from January 2004 to December 2021. Both the first and the second GKRS treatment were performed using the Gamma Knife Perfexion or Icon model with the stereotactic head G-frame and with a 4 mm collimator shot positioned on the cisternal segment of the trigeminal nerve. The median prescription dose at the first GKRS was 80 Gy, whereas a median prescription dose of 76 Gy was delivered at the second radiosurgery. Results We retrieved data from 31 patients with a mean age, at the time of the second treatment, of 64 years old; 16 patients (51.6%) were females. All patients except for one (96.8%) showed pain response after the first GKRS treatment, with Barrow Neurological Institute (BNI) pain scale grade I-IIIb. Two patients (6.5%) experienced BNI facial numbness scale grade IV hypoesthesia. Pain recurrence was observed after a mean of 28 months. All patients underwent a second GKRS, and all except for one (a different non responder compared to the first GKRS) had pain response with BNI pain scale I-IIIB (96.8%). However, after retreatment 8 patients (25.8%) reported BNI facial numbness scale grade 4 hypoesthesia. No patient experiences anesthesia dolorosa. After a minimum follow-up of 24 months, 61.7% of patients had controlled pain (BNI pain scale grade I-IIIb). Conclusions GKRS retreatment may be a feasible therapy for TN recurrency, albeit with a higher occurrence of bothersome facial hypoesthesia, compared to primary treatments. In our series, no patient displayed anesthesia dolorosa.

Introduction. Recent researches suggest that the anterior cingulate cortex and midcingulate cortex may play distinct roles in pain, emotion and memory regulation. DBS has become widely utilized not only for movement disorders but also in the treatment of some psychiatric disturbances, notably incredible chronic pain. Stereotactic bilateral anterior cingulotomy, including lesions in the anterior and midcingulate cortex, is one of the methods used for treating intractable pain syndrome of different ethologies. The aim of the study is to evaluate the effectiveness and safety of anterior cingulotomy for intractable pain. Material and methods. At the Romodanov Neurosurgery Institute, 9 patients with incredible chronic pain underwent stereotactic bilateral radiofrequency (RF) anterior cingulotomy. All patients were male. The mean age at surgery was 38.6 years (range 21-72 years). One patient had thalamic pain due to a low grade thalamic glioma, which course a severe contralatarel pain syndrome. The other eight patients had neuropathic pain resulting from direct nerve trauma; among them, four cases were related to mine blast injuries sustained in combat. Operations were performed using a CRW Stereotactic frame following MRI-CT fusion. Surgery was performed under general anesthesia with intravenous sedation.  Lesioning was conducted using a RF monopolar electrode with a diameter of 2.1 mm and a 3.0 mm bar tip. The areas for cingulate lesioning were identified bilaterally through direct targeting. The initial target was located 1.5 mm above the lower border of the cingulate gyrus, 6.5 mm lateral to the midline, and 20.5 mm posterior to the tip of the frontal horn. The lesion was made at 75°C for 60 seconds, then electrode was withdrawn to 2 mm above the target, and an additional lesion was made at the same temperature and duration. Three lesions were simultaneously performed bilaterally in the anterior cingulate gyrus, followed by two lesions targeted 5 mm anterior to the previous ones. Pain assessment was conducted using the 10-point Visual Analogue Scale (VAS) prior to surgery, at one and four weeks postoperatively in all cases, and at one year in 5 (56%) following treatment. Results. A significant reduction in pain syndrome was achieved in all cases immediately and four weeks after surgery with a 92% improvement on the VAS. At one-year follow-up, the VAS score showed an 82% improvement; only one patient experienced a partial recurrence of pain. There were no any operative complications, postoperative neurological and mood complications after operation. Discussion. Despite the study's limited sample size our results indicate that stereotactic RF bilateral anterior cingulotomy is a reliable and safe approach for managing incredible chronic pain of different aetiology.

Introduction: Trigeminal neuralgia is a disabling disease, which affects a significant proportion of the population (Incindece 5.5/100.000). The symptomatic treatment of the disease ranges from medical therapy (especially AED's and TCA's) to neurosurgical interventions such as percutaneous balloon compression, glycerol or RFT or even stereotactic radiosurgery. The only causative treatment of the disease is microvascular decompression through a retrosigmoid craniotomy. The classic approach utilises a microscope to visualise the neuro-vascular conflict in the prepontine cistern. However using a microscope allows great manoeuvrability and visualisation of the anatomical structures along the surgical corridor, it does not allow to visualise any structures behind an other one. Also using the microscope the surgical ergonomy is highly dependent on the positioning of the patient and the optimal distance from the surgical field. Methods: Here we present our multicenter experience with neuroendoscopic and exoscopic operations with a retrosigmoid craniotomy. The exoscope is a new device to allow microscope like magnification without the optical tubing of the microscope. Which was used especially during the craniotomy phase of the operation. The endoscope (4mm straight or 30 degree optic) was used typically during the decompression phase of the operation. Results: Exoscope is typically used during the first phase of the operation, which allows a more convenient operation posture for the surgeon and also microscope like magnification of the surgical field. However the exoscope also lacks the ability to "look behind" the structures. The endoscope gives in every single case added information about the anatomical situation and allows a better overview of the neuro-anatomical situation, especially in cases with narrow cisterns or complex neuromuscular conflict. We used both the endoscope assisted technique and also the endoscope controlled technique without the use of the microscope if the anatomical situation did require better intracisternal visualisation. Conclusion: There is abundant experience how to use the microscope during MVD procedures. Anyhow sometimes the microscope does not allow to overview the whole surgical field, especially in cases with narrow cistern or complex neuro-vascular conflict. In these cases the use of the neuroendoscope as an endoscope assisted technique may provide valuable information about the real situation, showing explicitly the neuro-vascular anatomy of the cerebellopontine cistern. The complete decompression of the initial segment of the trigeminal nerve with the dorsal root entry zone is crucial for the optimal outcome, therefore optimal visualisation is crucial for the best outcome. The exoscope is clearly adding to the comfort of the surgeon however the added benefit is limited due to the use of the same surgical corridor as the microscope. In summary in our hands the use of the endoscope in MVD operations's is the future and further training is necessary for the surgeons who are not familiar using an endoscope assisted technique.

Objective: There remains limited data on the long-term outcome of microvascular decompression (MVD) for refractory vagoglossopharyngeal neuralgia (VGN). There are no prospective or comparative studies. Here, we evaluate the effectiveness, safety, and long-term outcome of MVD in a consecutive series of patients with medically refractory VGN and compare these results with matched patients undergoing MVD for trigeminal neuralgia (TN). Methods: Overall, 11 patients with VGN underwent MVD, and these were matched by age and sex with patients with TN. Data included demographic features, pain characteristics, intraoperative findings, and clinical outcomes. Pain relief was assessed using the modified Barrow Neurological Institute (BNI) pain scale for both VGN and TN, with scores I-III defined as a good outcome. Results: At the time of the surgery, the mean age of patients with VGN was 58 years (range, 44-68), with a mean pain duration of 4,5 years. Intraoperatively, all patients had an arterial compression, most commonly from the posterior inferior cerebellar artery (10/11), followed by the vertebral artery (5/11). Arachnoid adhesions were present in both VGN and TN groups. Inclusively, two patients with VGN presented with concomitant TN, in which the cause was compression from the superior cerebellar artery. Immediate pain relief occurred in 10/11 patients, with good outcomes maintained in 9/11 patients at a mean follow-up of 56 months. Recurrence occurred in 3 patients in VGN, and in 2 patients with TN. One patient with recurrent VGN underwent successful posterior fossa re-rexploration 11 years after the index surgery. No significant differences in pain outcomes were found between patients with VGN and TN, and there was no difference in the rate of complications. Conclusion: MVD is an effective and safe procedure for VGN, leading to satisfactory pain relief with comparable outcomes in relation to MVD for TN. Besides the classical neurovascular conflict, arachnoid adhesions are a shared feature in both neuralgias, outstanding their importance in the pathophysiology of both cranial neuralgias.

Objective: The superior petrosal vein (SPV) is a common obstacle, obstructing the operative field during microvascular decompression (MVD) for trigeminal neuralgia (TN), and its management intraoperatively remains controversial. Here, we evaluate the safety of a specific rationale for dividing the SPV technique MVD for TN. Methods: We retrospectively analysed 217 patients who underwent first-time MVD for medically refractory TN. When a SPV was found obstructing the operative field, it was coagulated at the distal end of its main trunk near the entry site into the superior petrosal sinus, maintaining cross flow between the venous contributories. This technique was applied in 171 patients (79%) (group I), but not in the other 46 (21%) (group II). Data included demographics, clinical data, intraoperative findings, and postoperative complications were assessed and compared between both two groups. The defined primary outcome was the occurrence of venous-related complications. Results: The total cohort included 122 women (56%) and 95 men (44%), with a mean age of 60 years at surgery and a mean duration of pain of 79 months. In 216 out of 217 patients, the pain improved, and 213 were pain-free. Operative findings included an arterial conflict in 187 patients (86%), a venous conflict in 91 patients (42%), and arachnoid adhesions in 149 patients (68%). Three patients in the SPV-division group had a possibly venous-related complication: 1) asymptomatic small cerebellar hemorrhage, which was managed conservatively, 2) transient mild ataxia associated with a small infarct in the dorsolateral pons, and 3) transient mild ataxia due to an intracerebellar hemorrhage. There was no statistical difference in the overall complication rate between the groups. Conclusions: This study suggests that our approach of dividing the SPV at its main trunk while maintaining venous cross flow through its contributory veins is a safe strategy during MVD for TN. This approach improves visualization of the operative field without significantly increasing the risk of the dreaded venous-related complications, as previously reported in the literature.

PURPOSE Selective dorsal rhizotomy (SDR) and intrathecal baclofen (ITB) pump placement are two surgical options in children affected by spasticity secondary to cerebral palsy1. The latest literature is enlarging indication for SDR, given the amelioration in residual motor functions and helping everyday patients’ management and care. In case of ITB failure in non-ambulant patients, SDR represents an alternative to pump reimplantation to reduce spasticity and to facilitate patients’ care. METHODS A retrospective single-center study has screened all children diagnosed with spastic tetraparesis who underwent in the last 10 years SDR and had previously ITB pump implanted. A cohort of 6 patients was pooled out. Furthermore, pertinent literature has been reviewed. RESULTS Indication for pump removal was pump pocket’s infection, parents’ decision, poor response to ITB. Patients’ amount of lifetime with the pump implanted has been 6,9 years. It was statistically different the preoperative and postoperative Ashworth score in both procedures (p=0,005 and p=0,02). CONCLUSIONS Only 2 studies investigated pediatric population undergone SDR in occurrence of ITB pump removal. Authors are giving indication to SDR to a larger number of patinets, regardless GMFCS groups and previous ITB pump placement. In conclusion, SDR represents a valid tool in neurosurgeon’s hand to help ameliorating patients’ long-lasting quality of life, reducing the severity of the spasticity and leading to a better management by caregivers.

Objective: To evaluate the long-term effectiveness of selective tibial neurotomy (STN) for the treatment of the spastic foot using a goal-centered approach. Methods: Between 2011 and 2018, adult patients with a spastic foot (regardless of etiology), who received STN followed by a rehabilitation program were included. The primary outcome was the achievement of individual goals defined preoperatively (T0) and compared at 1-year (T1) and 5-year (T5) follow-up, using the Goal Attainment Scaling methodology (T-score). The secondary outcomes were the presence of spastic deformities (equinus, varus, and claw toes), the modified Ashworth scale (MAS) in the targeted muscles, and the modified Rankin score (mRS) at T0, T1 and T5. Results: Eighty-eight patients were included. At T5, 88.7% of patients had achieved their goals at least “as expected”. The mean T-score was significantly higher at T1 (62.5 ± 9.5) and T5 (60.6 ± 11.3) than at T0 (37.9 ± 2.8, p< 0.0001), and was not significantly different between T1 and T5 (p = 0.2). Compared to T0, deformities (equinus, varus, and claw toes, p< 0.0001), MAS (p< 0.0001), and the mRS (p< 0.0001) were significantly improved at T1 and T5. Compared to T1, only MAS increased slightly at T5 (p = 0.05) but remained largely below the preoperative value. There was no difference between T1 and T5 regarding other clinical parameters (deformities, walking abilities, mRS). Conclusion: This study found that STN associated with a postoperative rehabilitation program can enable patients to successfully achieve personal goals that are sustained within a 5-year follow-up period.

Background Tinnitus disorder, can lead to impaired quality of life and psychological suffering, especially when refractory to standard care. Deep brain stimulation (DBS) of the medial geniculate body (MGB) is a potential treatment for severe tinnitus by attenuation of pathological neuronal activity in the central auditory pathway. The aim of this pilot study is to assess the safety and feasibility of bilateral MGB DBS in patients with refractory tinnitus disorder. Methods This double-blind 2 × 2 cross-over study was conducted at Maastricht University Medical Centre, Maastricht, the Netherlands. Included patients had treatment refractory, severe and chronic tinnitus without an anatomical cause. Patients with bilateral MGB DBS were randomised to ON-OFF or OFF-ON as stimulation order for two cross-over phases. Primary outcome consisted of safety and feasibility. Secondary outcome on tinnitus severity, psychiatric and cognitive functioning and quality of life was assessed at screening, after both cross-over phases and at one-year follow-up. Results Four patients were included. No irreversible stimulation-induced side effects occurred. Surgical-related side effects were transient and resolved within two weeks. All patients experienced DBS as an acceptable treatment. Three of four patients showed improvement of tinnitus on the Tinnitus Functional Index. In the non-responder electrodes had the largest distance from the centre of the MGB. Conclusions This study shows that bilateral MGB DBS is safe and feasible for patients with refractory tinnitus. Findings suggest a potential of clinically meaningful reduction in tinnitus burden. However, effectiveness needs to be evaluated in a follow-up study.

Background: Studies assessing the effectiveness of selective tibial neurotomy (STN) assume that the procedure combined with a rehabilitation program, reduces foot spasticity and allows the achievement of personal goals. However, few studies reported failures in goal attainment, or spasticity recurrence, and no predictive factors have been established. Objectives: To identify predictors associated with the failure to achieve personal goals after STN and rehabilitation program. Methods: Eighty-eight adult patients with spastic foot, irrespective of the etiology, who underwent STN followed by rehabilitation program were included. Personal goals were assessed using the Goal Attainment Scaling methodology, with T-score calculated up to a 5-year follow-up. Spasticity recurrence was defined as a worsening of spasticity according to the modified Ashworth scale compared to the clinical status one year after STN. Clinical characteristics were analyzed to identify independent predictors, which were then confirmed using a logistic regression model. Results: At the 5-year follow-up, 10 patients (11.4%) had a T-score< 50. Logistic regression identified the degree of preoperative disability (modified Rankin Scale ≥ 3, p = 0.003) as the only significant predictor of failure to achieve personal goals was. Spasticity-free survival was significantly higher in patients who had achieved their goals at least as expected (p < 0.0005), suggesting a strong relationship between long-term functional gains and the sustained spasticity reduction. Conclusion: Failure to achieve personal goals after STN and rehabilitation program is rare. However, greater preoperative disability was identified as a predictor of goal attainment failure over time.

Introduction: Post-stroke motor disability remains a major challenge, with limited long-term efficacy of current rehabilitation strategies. This case report explores the potential role of deep brain stimulation (DBS) of the dentato-rubro-thalamic tract (DRTT) in reducing spasticity and improving motor function in a chronic stroke patient. Methods: A 56-year-old man with spastic hemiplegia and foot dystonia following a right hemispheric ischemic stroke in 2020 was treated with left-sided DRTT- cerebellar DBS after 3 years of unsuccessful botulinum toxin therapy and intensive rehabilitation. Preoperative assessments included Modified Ashworth Scale (MAS), Fugl-Meyer Assessment (FMA), Modified Rankin Scale (mRS), and Chedoke Arm and Hand Activity Inventory (CAHAI). A Medtronic DBS system was implanted targeting the left dentate nucleus. Results: Initial stimulation (130 Hz, 2.2 mA) combined with 6 weeks of rehabilitation resulted in reduced spasticity (MAS scores improved from 3–4 to 2–3), and gains in FMA (from 18 to 24) and CAHAI (from 44 to 49). Following frequency adjustment to 70 Hz and continued rehabilitation, further improvements were observed: FMA increased to 26, CAHAI to 50, and wrist MAS decreased to 3. Muscle mass gain in the biceps brachii and improved gait were also noted. Conclusion: DRTT-cerebellar DBS may offer a promising adjunctive therapy for post-stroke spasticity, particularly in cases resistant to conventional treatments. Further studies are needed to evaluate its efficacy and long-term outcomes.

Introduction: Anterior inferior cerebellar artery (AICA) vascular loops extending into internal auditory canal (IAC) are rare source of audio-vestibular symptoms and hemifacial spasms. There has been a controversary surrounding the clinical significance of AICA vascular loops into IAC. Here, we present our experience in 4 patients who presented with symptoms of cranial nerve 7 and 8 compression from AICA vascular loops. Method: A retrospective analysis of cases performed in last 6 months since starting first post-fellowship faculty position were reviewed and patients were identified with AICA vascular loops extending into IAC. Clinical presentations and surgical outcomes were reviewed. AICA vascular loops were graded based on previously established grades: 1) grade 1 – lying only in cerebellopontine angle but not entering IAC, 2) grade II – entering IAC but less than 50%, 3) grade III – extending more than 50% into the IAC. Results: 4 patients were identified with AICA vascular loops extending into IAC. 75% were female, aged ranging from 28 – 77yrs. 75% had grade II loops. Most common symptoms were tinnitus and vertigo which were present in all patients, followed by hemifacial spasm (HFS) in 75% and hearing loss in 25%. All patients had failed medical management and referred by our neurology colleagues. All patients underwent endoscopic assisted retrosigmoid craniotomy for microvascular decompression. AICA loops were identified ventral to the 7/8 complex. Arachnoid dissection was performed. Loops were gently retracted out of IAC and secured with Teflon pledges. The loops are tethered through the labyrinthine artery originating at the tip of the loop. The loops tend to recoil back into the IAC and should carefully be monitored with Valsalva maneuvers to ensure they remain in place. All patient noted complete resolution of tinnitus and vertigo, HFS resolved in 1 (33%) and improved in (67%). Most common complication was transient hearing loss (50%). Hearing loss happened in a delayed fashion in 3-4 weeks and started noting improvement over 2 months. Conclusion: AICA loops extending into IAC are rare causes of audio-vestibular symptoms and HFS. These patients should be carefully evaluated in conjunction with neurology and radiographic findings closely reviewed. Neurophysiological monitoring should be used in all cases. Vascular loops should be carefully handled, making sure not avulse labyrinthine artery originating from the vascular loop. These patients respond very favorably to surgical management.

Spasticity is a complex neurological disorder that arises from upper motor neuron lesions and manifests as involuntary muscle overactivity, leading to impaired motor control, posture, and functional independence. It is commonly associated with cerebral palsy (CP), spinal cord injury (SCI), stroke, multiple sclerosis (MS), and traumatic brain injury (TBI). While conservative treatments such as oral medications, botulinum toxin injections, and physiotherapy remain first-line, a significant subset of patients with refractory or severe spasticity benefit from surgical interventions. These target either neural circuitry (e.g., intrathecal baclofen [ITB], selective dorsal rhizotomy [SDR], spinal cord stimulation [SCS], neurotomy) or secondary soft tissue changes (orthopedic procedures). This study aimed to analyze the historical evolution, scientific impact, and thematic development of neurosurgical techniques for spasticity through bibliometric analysis. We conducted a structured search of the Scopus database on March 1, 2025, using terms “surg* AND spastic*” and “spinal cord stimulation AND spastic*”, including only articles focused on human subjects and published in English. From 2362 initial records, 1049 documents (1951–2024) were selected, comprising 927 original articles and 110 reviews, involving 3229 unique authors across 318 publication sources. Bibliometric analysis and visualization were performed using Bibliometrix, VOSviewer, and Scimagographica. Scientific production showed exponential growth, particularly from the 1990s, with a peak in 2023. While the global citation average has declined in recent years—likely due to publication volume increase and citation lag—key studies remain highly influential. Most-cited papers include those by Coffey et al. (1993) and Albright et al. (2003), which established ITB therapy as a cornerstone in diffuse spasticity management. Similarly, literature by Peacock et al. and Park et al. established SDR as a safe and effective option, particularly in pediatric CP. In the neurosurgical subgroup, SDR was the most reported intervention (n=171, 35.9%), followed by ITB (n=99, 20.8%) and neurotomy (n=67, 14.1%). More recent publications explore nerve transfer techniques (e.g., Zheng et al., NEJM 2022), suggesting future directions toward reconstructive strategies. Geographically, the United States has historically dominated this field, with 744 publications, followed by China (313), France (258), and the United Kingdom (145). Notably, China has shown a marked increase in output since 2018. Fudan University (Shanghai) was the most prolific institution (83 publications), followed by the University of Lyon and VU Medical Center Amsterdam. Author analysis identified Sindou M (France) as the leading neurosurgical contributor with 42 publications, influential for his work on rhizotomy and neuromodulation. Keenan MA and Miller F led in orthopedic contributions, underscoring the multidisciplinary nature of spasticity surgery. Keyword co-occurrence and thematic mapping revealed “spasticity” and “cerebral palsy” as central themes. Six keyword clusters were identified: 1) surgical treatment of spasticity, 2) neuromodulation and rehabilitation, 3) peripheral nerve techniques including neurotomy, 4) SDR and intraoperative monitoring, 5) nerve transfer, and 6) spinal cord management with ITB. Emerging topics such as contralateral cervical nerve transfer were categorized as niche, indicating novelty and limited current integration into clinical practice. Thematic mapping identified “selective neurectomy” and “SDR” as motor themes—both highly developed and central. Conversely, “contralateral seventh cervical nerve transfer” represented a promising but underexplored area. Overall, neurosurgical journals such as Child’s Nervous System, Journal of Neurosurgery, and Neurosurgery featured prominently, demonstrating the high quality and impact of neurosurgical contributions. This analysis highlights the dynamic and expanding landscape of neurosurgical strategies for spasticity. It underscores the dominance of SDR and ITB over the decades while revealing a growing interest in advanced neuromodulation and nerve reconstructive procedures. The study also emphasizes the crucial role of interdisciplinary collaboration and suggests underutilized research avenues ripe for exploration.

Purpose: Magnetic resonance imaging developments for optimal targeting of stereotactic surgical approaches for tremor have yielded white matter attenuating sequences (FGATIR/FLAWS) directly showing a targetable hyperintensity in the subthalamic region (rubral wing, RW). The RW has been reported to coincide with the dentato-rubro-thalamic tract (DRT) without determining its exact portion (crossed, DRTx or uncrossed, DRTu). RW discernibility on the single subject level might be hampered due to low signal-to-noise ratio (SNR), potentially interfering with surgical outcomes. Methods: We performed manual delineations of RW on FLAWS sequences in native space (n=77, 3 raters) and warped results into MNI 152. From this tractographic analyses of DRT (human connectome project body, n=1000) were carried out, using the red nuclei and RW as waypoints. In another approach, we investigated fiber tightness peaks of DRTX vs DRTu portions along their z-axis. Results: Identification of RW was possible in all subjects. DICE coefficient for volumetric comparison was rather low with 0.54. Euclidean distance of the RW center of gravity (COG) between raters was <2mm. Tractographically, RW represents an optimal waypoint to define DRTx with optimal constraining fibers to the ipsilateral precentral gyrus (PCG). A peak for fibers descending from PCG (DRTx only) was found to coincide with RW. Conclusions: COG can be determined with good accuracy, but full volumetric appreciation is difficult on the single subject level (SNR), potentially necessitating additional DRT tractography for surgical targeting. In the light of this connectomic study, the RW‘s role as a valid and individually visualizable tremor target for DBS and SLS is strengthened. In a way, the application of the FLAWS/FGATIR delineation of RW would potentially allow surgeons to rely on a more generic personalized MRI grey sequence based and geometrically accurate targeting for tremor without a cumbersome use of the more demanding DWI technology. However, the volumetric interpretation of the structure might not be unequivocal (especially in its anterior-posterior extensions) and care must be taken to readily identify the structure on a single case basis. This potentially necessitates the further use of adjunct imaging modalities (DWI) in cases of a low quality RW depiction with FLAWS/FGATIR to avoid detrimental side effects.

Millimetric precision is fundamental to functional stereotactic neurosurgery and research. This relies on accurate identification of deep brain targets, which in turn often requires time-intensive manual segmentation, machine learning generalisability, and atlas limitations. We introduce RegiNet, our novel deep learning framework, addressing three critical issues. First, rapidly and robustly generating patient-specific deep brain nuclei segmentations across varied magnetic field strengths and MRI protocols. RegiNet, integrating subject-specific anatomical priors into a transformer-based model, demonstrates high fidelity for the subthalamic nucleus (STN) (Dice Similarity Coefficient (DSC) 0.94, 95th percentile Hausdorff Distance (HD95) 1.64 mm). This performance significantly outperformed three leading academic and industry segmentation algorithms by >28% on exclusively clinical STN-DBS scans (N=120). For thalamic nuclei—Ventral intermediate (Vim), Ventro-oral (Vo), and Ventro-posterior (Vp)—using multimodal inputs like fractional anisotropy maps, RegiNet achieved a mean DSC of 0.87. Crucially, HD95 values were consistently below the 2.0 mm surgical accuracy threshold (mean HD95: Vim ~1.36 mm, Vo ~1.60 mm, Vp ~1.62 mm). Second, domain shift, which degrades segmentation model performance across imaging centers, slowing adoption and necessitating burdensome, site-specific retraining. RegiNet’s architecture demonstrates inherent cross-scanner/protocol robustness. In leave-one-out experiments testing adaptability to unseen field strengths (1.5T, 3T, 7T), RegiNet retained an average DSC performance of 82% and never produced null predictions, unlike baseline models which showed significant degradation and failures (e.g., SwinUNETR 72% retention with 10 nulls, DINTS 49% with 16 nulls). On completely unseen external data (N=476), RegiNet achieved 86% performance retention, starkly contrasting with SwinUNETR (48% retention, 26% failure rate). This was evidenced by successful segmentation from T1w/T2w and fractional anisotropy maps, maintaining performance across diverse scanner vendors. Our methods may offer rapid adaptation to site-specific protocols without extensive manual annotation, reducing retraining needs. Third, the inadequacy of standard atlases (e.g., HCP-1065 from young healthy adults) for patients with disparate neuroanatomy, like older individuals with thalamic atrophy. Comparing RegiNet-derived Vim segmentations in our Parkinson's disease tremor (PDT) and Essential Tremor (ET) patients (N=45) against HCP-1065 templates (coordinates relative to AC-PC, Asymmetric MNI 2009b space) revealed substantial differences. RegiNet left Vim centroid (X=-13.62, Y=-18.43, Z=-2.38 mm) versus HCP-1065 (X=-14.36, Y=-18.20, Z=-1.58 mm) showed 1.11 mm displacement and 2.12 mm boundary disagreement (HD95). Right Vim showed 1.28 mm centroid displacement (RegiNet: X=13.12, Y=-17.56, Z=-2.56 mm; HCP-1065: X=14.14, Y=-17.40, Z=-1.80 mm) and 2.87 mm boundary disagreement. Our population-specific Vim locations were consistently more posterior/inferior, with >2 mm boundary disagreements, quantifying standard atlas mismatch. These results quantify potential systematic errors in normalised diffusion/quantitative MRI where patient-specific scans can be scarce. RegiNet offers robust, precise, subject-specific analysis, pivotal for advancing large cohort studies where accurate individual segmentations are often infeasible.

Objectives: To compare the performance of Brainlab’s commercially approved planning software with the newly developed CranioPass software in stereotactic neurosurgical planning for tremor treatment in patients unresponsive to medication and eligible for Deep Brain Stimulation (DBS). Methods: Twelve patients (8 male, 4 female; mean age 62.8 ± 11.9 years) with a mean tremor duration of 7.5 ± 5.5 years (range: 4–22) were included. Diagnoses included secondary Parkinson’s syndrome (6), essential tremor (2), dystonic tremor (2), Parkinson’s disease (1), and post-thalamic hemorrhage (1). Nine patients underwent bilateral DBS lead implantation; three had right-sided implantation. Electrodes were implanted in GPi (1 patient), STN (1), and Vim-PSA (10). Six patients received the Infinity 7 system (Abbott, USA) and five received the Vercise Genus system (Boston Scientific, USA). Postoperative CT scans were performed one day after surgery and fused with preoperative stereotactic CT for target verification. Target coordinates were calculated using both Brainlab and CranioPass software and compared using the Riechert-Mundinger (RM) target point simulator. Lead tip positions on CT were compared with planned coordinates. Tremor was assessed using the Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) at baseline, 4 weeks, and 16 weeks postoperatively. Results: Among 21 implantations (12 left, 9 right), coordinate differences between the two software platforms were minimal. A 0.1 mm difference in the Z-axis was observed in one case. Arc settings were identical in 13 cases; A 0.1-degree difference has been observed in one parameter in 3 settings on the left and in 3 settings on the right side. In two values (0.2 and 0.1 degree) in 1 setting, and 0.1 and 0.1 degree in 1 setting. The average deviation between planned and actual lead tip positions was 0.7 ± 0.6 mm (left: 0.6 ± 0.7 mm; right: 0.8 ± 0.6 mm), which falls within the voxel size of the imaging datasets. FTMTRS scores showed an 87.5% improvement at 16 weeks, confirming clinical effectiveness. Conclusions: CranioPass demonstrated high accuracy and consistency compared to Brainlab software in stereotactic planning for DBS. Surgeries based on CranioPass planning were successfully completed with no adverse events. These results suggest CranioPass is a reliable alternative for stereotactic DBS planning, supporting its potential for broader clinical use.

Intact cerebral microcirculation is a key function for vital neural tissue. The cerebral microcirculation can be measured with laser Doppler flowmetry (LDF). Our research group has adapted an LDF system for use in relation to neurosurgical intervention that can investigate the microcirculation and act as a “vessel alarm” during stereotactic and functional neurosurgery. The aim is to give an overview of the system and give examples of applications already implemented and to suggest potential future applications. The system comprises a LDF module (PF5010/PF6010, Perimed AB, Sweden) with an inhouse developed software (Labview/MatLab) for data collection, storage and real-time visualization of tissue Perfusion (microcirculation) and TLI (total light intensity, grey-whiteness). A set of optical probes have been designed. Probes are available for stereotactic guidance and creation of a trajectory in relation to deep brain stimulation (DBS) implantations, and stereotactic and neuronavigated brain tumor biopsies. In the latter set up the probes are adjusted to the inner cannula of a biopsy kit modified with an opening at the tip. The opening allows forward looking measurements in tissue not yet touched by the probe. The system has been used in more than 130 DBS implantations and 50 brain tumor biopsies. As all probes are “forward looking” the microcirculation is recorded about 1 mm beyond the probe tip. Data is presented in real-time on a monitor during surgery. If necessary, e.g. due to very high Perfusion, the trajectory can be changed to avoid a hemorrhage. As the probe is securely fastened to the stereotactic device or neuronavigational system potential movement artifacts are reduced to a minimum. In addition, the TLI signal acts as an in-situ tracer of tissue grey-whiteness and can together with the Perfusion signal support in intraoperative guidance through brain structures during insertion of the probe. The system has a resolution of 0.5 mm, which makes it possible to detect changes in grey-whiteness between e.g. thin laminae in the pallidum and thalamus. Additional applications not yet explored are cell line implantations, drug administration, RF-lesioning and guidance during LITT. In principle all types of stereotactic interventions are candidates for use of the LDF-system. In conclusion, micocirculation measurements can together with grey-white matter identification help the surgeon avoid vessels along a trajectory. It can also be used to study cerebral microcirculation in healthy and diseased tissue in relation to stereotactic and functional neurosurgery.

Background In Parkinson's disease (PD) patients, modulation of the fibre tracts of the cortico-basal ganglia-thalamo-cortical loop is the presumed mechanism of action of deep brain stimulation (DBS) of the subthalamic nucleus (STN). Therefore, we explored patient-individual cortical structural connectivity of the volume of tissue activated (VTA), as well as DBS-induced modulation of fibre tracts connecting the STN with cortical and sub-cortical nodes and their correlation with therapeutic effects. Patients and Methods A retrospective cohort of n = 69 PD patients treated with bilateral DBS of the STN was analysed. Clinical response was assessed from the DBS-induced change in the UPDRS-III motor scores (total and symptom-specific sub-scores for tremor, rigidity, and bradykinesia) under regular medication after a median follow-up of 9.0 (range 2.6 – 20.2) months. Tractography based on patient-individual diffusion-weighted MRI was employed in two ways. Firstly, whole brain tractography was used to identify the cortical connections of fibres passing the VTAs. Then, reconstruction of specific white matter pathways of the motor loop connecting the STN with the basal ganglia and cortex (informed by the regions obtained by the first analysis) were used to identify the proportion of fibres within these pathways which was modulated by STN-DBS. This proportion of pathway modulation was used in a correlative analysis with clinical outcomes. Results Streamlines traversing the VTAs were primarily connected to the supplementary motor area (SMA), pre-SMA and the premotor cortex. Streamlines from both primary motor (M1) and sensory (S1) cortices were also identified, but to a much lesser degree. Within the pathways connecting the STN with the cortical and subcortical nodes, on average 30-40% (range 10-80%) of the fibres were modulated by STN-DBS. This proportion correlated significantly with the percentage change in UPDRS motor score for fibres connecting the STN to cortical regions like the SMA (ρ=0.28), pre-SMA (ρ=0.26), and ventral and dorsal pre-motor cortices (ρ=0.26 and ρ=0.29, respectively). Interestingly, modulation of the pathways between the STN and the globus pallidus externus (GPe, ρ=0.26) and internus (GPi, ρ=0.29) also showed significant correlation to UPDRS motor improvement. Finally, good clinical responses for both tremor and rigidity were associated with a significantly (p < 0.05) higher proportion of modulated fibres for the same cortico- and sub-cortico-STN connections. Conclusions Patient-individual tractography reveals that, in PD, most of the cortical fibres traversing the VTA are connected to the SMA. In addition, clinical efficacy is related to the proportion of DBS-affected fibres connecting the STN with nodes of both the hyperdirect (cortex-STN) and the indirect pathways (STN-basal ganglia). As such, patient-specific tractography, in particular of the basal ganglia, could be used in a clinical context as a tool to guide therapy. Funding: Funds have been provided by the European Joint Programme Neurodegenerative Disease Research (JPND) 2020 call “Novel imaging and brain stimulation methods and technologies related to Neurodegenerative Diseases” for the Neuripides project ‘Neurofeedback for self-stImulation of the brain as therapy for ParkInson Disease’.

Background: Convection-enhanced drug delivery (CED) for Parkinson's disease (PD) is costly, and current methods lack precision, often targeting the entire putamen, leading to the potentially inefficient use of resources. Our study addresses this by exploring a more targeted approach for drug delivery, which could reduce treatment costs by focusing therapy on specific regions of putamen. By optimizing drug delivery, we aim to make treatments more cost-effective without compromising efficacy. Methods: Twenty PD patients underwent diffusion-weighted imaging (DWI) to visualize the structural connectivity within the brain. A commercial subcortical auto-segmentation tool was used to define the putamen as well as the amygdala, the STN, and the cerebellum. Utilizing the Julich Brain Atlas, nine cortical regions (Brodmann areas 44, 45, 3a/b, 4a/p, pre-SMA, SMA, and insula) were semi-automatically segmented. Structural connectomes were analyzed through tractography, allowing for the parcellation of the putamen into four segments in relation to the anterior commissure. Two trajectories, occipital and frontal, were tested for segment coverage using stepwise injection of the therapeutic agent. A genetic algorithm was employed to simulate these injections and to compare the coverage of the target region. Results: Tractography revealed a significant projection of motor areas to the superior posterior segment of the putamen, suggesting this region as a more specific target for treating motor symptoms in PD via CED. Non-motor connections were most common in the inferior posterior segment for the amygdala and in the superior anterior segment for the insula. Both occipital and frontal trajectories were found to be equally feasible for targeting the putamen segments, with surgical feasibility varying by individual patient anatomy, and achieved comparable coverage, with no significant difference between them, highlighting the need for personalized surgical approaches. Conclusions: The application of DWI and tractography for the segmentation of the putamen by its cortical connections offers a pathway towards targeted gene therapy in PD. Identifying the posterior superior segment as the primary recipient of motor area projections and confirming the feasibility of using either the occipital or frontal trajectory underscores the flexibility in optimizing therapeutic efficacy while conserving resources. This precise targeting could potentially allow for reduced dosages and more focused treatment, minimizing exposure to non-motor segments of the putamen and associated risks.

【Introduction】 In stereotactic thalamic surgery, accurate identification of the target subnuclei significantly affects therapeutic outcomes. However, the boundaries of these subnuclei are often ambiguous and challenging to visualize with conventional MRI. For tremor treatment targeting the ventral intermediate nucleus (Vim), tractography is frequently used to delineate the dentatorubrothalamic tract (DRTT) as a reference. Nonetheless, distinguishing the DRTT from the posteriorly located medial lemniscus (ML) remains difficult and reproducibility is limited. In this study, we investigated the utility of FGATIR MRI imaging as a tool to clearly differentiate the DRTT from the ML and compared the results with Klüver-Barrera-stained human brain sections. 【Methods】 We compared preoperative MRI images used for planning MRI-guided focused ultrasound (FUS) thalamotomy with previously prepared human brain specimens. MRI scans were acquired using a Siemens MAGNETOM Lumina scanner, including 3D T2 Cube, 3D SPGR, DTI, and FGATIR sequences. Human brain specimens were sectioned into continuous frozen slices at 50 μm thickness, with every 500 μm slice stained using the Klüver-Barrera method and digitized. FUS thalamotomy was then performed, and the validity of the preoperative MRI images was evaluated by postoperative MRI and clinical outcomes. 【Results】 Among the preoperative imaging modalities, FGATIR provided excellent visualization of intrathalamic fiber tracts. Postoperatively, tremor was completely resolved without any adverse events such as sensory disturbances. MRI confirmed the lesion localized to the Vim including the DRTT, while the ML remained identifiable and unaffected. 【Discussion】 In tremor treatments targeting the Vim, the therapeutic "sweet spot" often lies near the boundary with the posterior ML, increasing the risk of sensory side effects when seeking maximal efficacy. For FUS, where microelectrode recording cannot be performed, visualizing the ML boundary is particularly important. FGATIR imaging may provide more accurate visualization of the ML within the thalamus compared to tractography.

Introduction: Deep brain stimulation (DBS) is a therapy for neurological disorders, with accurate electrode placement being key to its success. Poor electrode placement accounts for up to 46% of treatment failures.[1] Most DBS workflows use co-registration (‘fusion’) of preoperative MRI with perioperative CT for planning and evaluating electrode placement. However, inherent differences between CT and MRI present challenges to image registration algorithms. While CT provides excellent bone contrast, MRI renders bone tissues as nonspecific low signal structures in most sequences.[2] Moreover, while intraoperative CT has increased surgical efficiency, its lack of soft tissue contrast results in co-registration based exclusively on bone signal, compounding this problem.[3] Zero echo-time (zTE) imaging, a novel MR technique, enables precise reconstruction of cortical bone.[4] zTE achieves this via efficient capture of short-lived bone signal and uniform soft-tissue response. Here, we present an optimised zTE sequence (with preserved brain tissue contrast), applied to our DBS surgical workflow. Methods: We optimised and implemented a brain zTE sequence in our preoperative DBS protocol (Figure 1). 25 consecutive patients who underwent DBS following the novel imaging protocol were included (targets: STN, GPi, VIM, PPN). For initial validation, CT to T1-MPRAGE co-registration was performed in FSL-FLIRT[5] (6 degrees-of-freedom (DOF), normalised mutual information (nMI) cost function) with- and without the zTE image as an intermediate step i.e. CT-T1 and CT-(zTE)-T1, Figure 2. To directly assess impact on our clinical workflow, two separate stereotactic plans were created per patient using Renishaw NeuroInspire™: with either T1-MPRAGE or zTE as the base sequence. This generated similar CT-T1 and CT-(zTE)-T1 co-registrations (6DOF, nMI).[6] Registration accuracy was evaluated by: a) Extraction and quantification of registration and cost function matrices (CT-T1 vs. CT-(zTE)-T1) b) Calculation of Dice similarity coefficients of overlap between segmented skull structures (CT-T1 vs. CT-(zTE)-T1) c) Blinded anatomical landmark-based assessment by an Attending Neurosurgeon Results: a) The root mean square difference between CT-T1 and CT-(zTE)-T1 registration matrices across the cohort was (i) 1.10mm (95% CI 0.88 – 1.32, p<0.0001, two-tailed t-test) in the clinical workflow (Renishaw NeuroInspire) and (ii) 0.77 mm (95% CI 0.64 – 0.91, p<0.0001, two-tailed t-test) in the FSL-FLIRT pipeline. Euclidean errors for electrode contacts tips on postoperative imaging were similar in magnitude (p<0.05). b) Dice similarity coefficients for segmented skull structure overlap were greater for CT-(zTE)-T1 vs CT-T1 across the cohort (p<0.05). c) In the blinded qualitative expert evaluation, CT-(zTE)-T1 outperformed CT-T1 in 15/23 patients, with no discernible difference in the remainder. There were no instances of CT-T1 outperforming CT-(zTE)-T1. Discussion and Conclusions: We optimized a novel MRI sequence with clear delineation of bony anatomy and neuraxial structures (Figure 1). The addition of zTE to our DBS surgical workflow has resulted in a statistically significant difference in CT-MR co-registration, with improvements in registration accuracy. The clinical significance of this difference is currently under prospective investigation. While <2mm accuracy is considered acceptable in the movement disorders literature,[7] optimising image co-registration is an important component of reducing planning error and more accurately evaluating DBS targeting postoperatively. A limitation of this study is the lack of ground-truth structural information, leading to the use of Dice overlap coefficients and qualitative expert evaluations. An ongoing study with MR/CT fiducials and phantoms seeks to address this (to be discussed). Finally, we will discuss current development work on postoperative zTE, which can better localize DBS electrodes than existing MR methods (Figure 3). This could be utilised in postoperative MRI protocols. References: 1. Okun MS et al. (2005) Arch Neurol. PMID: 15956104 2. Florkow MC et al. (2022) J Magn Reson Imaging. PMID: 35044717 3. Kremer NI et al. (2019) Neuromodulation. PMID: 30629330 4. Wiesinger F, Ho ML (2022) Br J Radiol. PMID: 35616709 5. Jenkinson M et al. (2012) Neuroimage. PMID: 21979382 6. Geevarghese R et al. (2016) Stereotact Funct Neurosurg. PMID: 27318464 7. Kremer NI et al. (2023) J Neurol Neurosurg Psychiatry. PMID: 36207065

Background: Tractography is a non-invasive method for reconstructing and visualizing white matter tracts based on MRI imaging. The use of tractography as a clinical and research tool is increasingly growing, presenting promising results for targeting and improving neuromodulation procedures outcomes. Moreover, white matter characterization plays a key role in exploring and understanding normal populations and brain disorders, while multiple macroscopic and microscopic features of the tracts can be extracted. However, to date, while different tracts may contain thousands of fibers, the common approaches to tract parameters analysis are summarizing the tract with a single mean value or performing 1D along-tract analysis, which may result in loss-of-data and minimize its clinical value. Methods: 10 MRI scans of healthy subjects from the Human Connectome Project database, and 4 from Rambam Health Care Campus were acquired. Utilizing the DTI sequence, a tractography analysis of six tracts was performed for each subject bilaterally. An algorithm written in Matlab™ was built for tract characterization and inter-subject comparison of the tracts. The algorithm performs a 3D analysis of a tract while using its spatial and geometrical information to gather and integrate data. It utilizes the anatomical position along the tract, its morphology, and the angle around it to calculate and highlight the tract characteristics in a 3D fashion. The algorithm was applied to various tracts (motor and limbic) that highly differ in morphology, and statistical analysis was performed. Results: A method for 3D or 2D visualization of white matter tracts geometrical and microstructural features, generating 616 different maps. Utilizing the method for fractional anisotropy analysis yielded maps with a unique pattern for each of the six tracts, while preserving high inter-patient reproducibility. This method provides a comprehensive observation of a tract and its surrounding structures, an inter-subject comparison of different tracts through various parameters, and a tool for abnormalities detection, while projecting the results on the patient or MNI space anatomy. Conclusions: We present an innovative tool for analyzing white matter tracts. This tool may contribute to the research of white matter tracts, the understanding of various disorders, the detection of biomarkers, targeting, and even diagnosis.

Deep brain stimulation (DBS) has become essential to treat movement disorders. As technology evolves for an ever-finer modulation of pathological networks, increasing numbers of lead contacts and directionality complexify manual programming. Therefore, automated algorithms are being evaluated to predict DBS parameters based on probabilistic sweet spots. As a preamble, such software requires accurate co-registration between pre- and postoperative images, reliable brain volume normalization, brain shift correction and precise electrode detection. This computational workflow is already embedded in tools dedicated to DBS research – such as Lead-DBS. However, its robustness between distinct postoperative CT scans at the individual level has not yet been assessed systematically. To test the robustness of the image-processing workflow applied in Lead-DBS, we identified 34 retrospective patients (68 hemispheres) with Parkinson’s Disease (PD) or Essential Tremor who were implanted with DBS electrodes and received two distinct postoperative CT scans. Each of these two scans was processed independently in Lead-DBS (v3.1) for electrode reconstruction, using the same preoperative MRI as reference. At the individual level, the computed coordinates of the lead tip were compared between image sets, as well as the resulting volumes of tissue activated (VTA) based on patients’ effective stimulation parameters. At the group level for PD patients, we computed and compared probabilistic maps of clinical improvement, based on the first or second postoperative CT scan respectively, using the same clinical data. Between image sets, lead tip coordinates in the normalized space showed a mean translation of 0.78mm (min 0.21mm, max 1.70mm). In our dataset, the robustness of lead reconstruction was not significantly influenced by pneumocephalus, as we compared subgroups with or without intracranial air on the first postoperative CT. No significant correlation could be drawn between the extent of lead translation and the pneumocephalus volume. To assess the relevance of up to 1.70mm lead tip translation, VTAs were computed and compared between postoperative image sets. The mean Dice index was 0.73 (min 0.33, max 0.94). In the twenty hemispheres with lead tip translation of 1mm or more, the Dice index was systematically below 0.75. At the group level of PD patients, the two computed probabilistic maps were overlapping without significant discrepancy. From this robustness study, we conclude that brain shift correction algorithms are reliable, as no significant lead translation could be imputed to pneumocephalus. As VTA computation varies in a mean range of 27% at the individual level, the current co-registration, normalization and lead detection workflow still requires some improvement to serve as a robust base for automated DBS parameter prediction. However, the variability of lead reconstruction disappears at the group level and the current image processing workflow seems sufficient to compute probabilistic maps of clinical improvement – and therefore sweet spots. Future studies with postoperative MRI instead of CT may show better robustness of lead reconstruction at the individual level.

Objective: Although brain shifts can occur during deep brain stimulation (DBS) electrode implantation in the subthalamic nucleus (STN), the underlying causes and predictive factors for these shifts remain unclear. In this study, we utilized an index derived from X-ray films and software analysis to quantify the degree and direction of changes in the implanted electrodes relative to the STN and investigated potential clinical factors associated with these shifts. Methods: We analyzed 42 DBS electrodes implanted in the STN of 21 individuals with Parkinson’s disease. Electrode tip displacement was evaluated using Elements (BRAINLAB®️) software based on computed tomography (CT) scans obtained immediately after implantation (1st CT) and after complete dissipation of intracranial air (2nd CT), comparing the two images (2nd CT – 1st CT). We used “Angle A,” measured from the anterior and posterior commissure line and horizontal plane on X-ray films, along with intracranial air volume obtained from Elements software, as predictive factors for brain shifts. Results: The x-coordinate of the electrode tip shifted significantly in the lateral direction (0.4 ± 1.12 mm, p = 0.025), while the y- and z-coordinates shifted significantly in the anterior (1.35 ± 0.84 mm, p < 0.0001) and caudal (0.54 ± 0.63 mm, p < 0.0001) directions, respectively. The displacement in the y-coordinate significantly correlated with both intracranial air volume (p = 0.001, R = 0.476) and Angle A (p = 0.047, R = -0.308). The z-coordinate displacement correlated with intracranial air volume (p = 0.049, R = 0.305), although this correlation had limited statistical power. The x-coordinate displacement did not correlate with any assessed factors. Conclusion: Electrodes implanted in the STN shifted laterally, anteriorly, and caudally following the resolution of intracranial air. Minimizing intracranial air entry through burr holes and maintaining the head position closer to the horizontal plane may help mitigate brain shifts during STN DBS implantation.

INTRODUCTION Preoperative and intraoperative identification of eloquent areas near supratentorial lesions is standard practice in pediatric patients, particularly for motor and language mapping. Non-invasive tools such as transcranial magnetic stimulation (TMS) and DTI-based fiber tracking enhance surgical planning, while intraoperative techniques like neuromonitoring, neuronavigation, and intraoperative MRI support safe resections. This abstract presents the role of motor mapping with navigated TMS (Nexstim®) at Hospital Sant Joan de Déu (Barcelona), with results integrated into the surgical planning platform and used intraoperatively (Fig. 1). MATERIALS & METHODS Patients with supratentorial lesions were prospectively recruited from the surgical program. All underwent a diagnostic 3T MRI, with additional studies (fMRI, DTI, and nTMS) ordered based on lesion location and clinical presentation. nTMS is a non-invasive technique using magnetic stimulation with image-guided navigation to map the motor cortex. Muscle responses or MEPs (Motor Evoked Potentials) were recorded via electromyography and saved as spatial coordinates. These data were imported into the Brainlab Node® platform for co-registration, segmentation, and tractography using anatomical and/or functional ROIs. The resulting 3D model was used for planning and transferred to the Brainlab Dual Curve® system for intraoperative navigation (Fig. 2). Intraoperative motor mapping was performed using direct cortical stimulation (DCS, Inomed®) over suspected motor areas. Preoperative and intraoperative data were correlated by registering intraoperative coordinates using the Brainlab® navigated pointer (Fig. 3). RESULTS Between March 2022 and January 2025, 29 pediatric patients (ages 3–18, mean age 9.87) with supratentorial lesions were prospectively enrolled. All underwent preoperative motor mapping with nTMS. 38% (n = 11) were male and 62% (n = 18) female. Most (90%) had drug-resistant epilepsy associated with structural or tumor-related lesions; 10% (n = 3) had tumor pathology without epilepsy. Lesions were in the left hemisphere in 72% (n = 21) and right in 28% (n = 8). In 25 patients (86%), the motor cortex in the lesioned hemisphere was successfully localized. In 4 cases (13.7%), mapping failed due to poor cooperation—an inherent limitation in pediatric populations. 86% (n = 25) underwent surgery: 2 hemispherotomies, 10 tumor or epilepsy resections, and 11 laser ablations. Only hemispherotomies and resections were neuromonitored, so tractography and functional data were crucial for laser procedure planning. Of the successful mappings, 76% (n = 19) were imported into Brainlab for functional CST tractography. Customized tracts were derived from 3D functional ROIs; anatomical CST tracts were also generated using anatomical motor ROIs. In 12 cases, both methods were combined. All cases with tractography were navigated intraoperatively. Postoperative outcomes were consistent with planning: 64% had no motor deficits, and 36% had temporary, anticipated deficits (e.g., hemiparesis). In 3 cases, preoperative mapping was confirmed intraoperatively via DCS (Inomed®), validating functional localization. DISCUSSION Preoperative mapping is essential in pediatric epilepsy surgery, enabling precise localization of the motor cortex to avoid damaging eloquent areas. This reduces the risk of postoperative deficits such as paralysis or weakness. It also supports individualized surgical planning, accounting for age-dependent anatomical and functional variability. Functional maps guide tailored resections or ablations, minimizing the risk to non-epileptogenic motor areas. Correlating preoperative nTMS with intraoperative DCS provides an added layer of confidence, reinforcing a function-preserving, personalized surgical approach.

Topic: Subthalamic Nucleus Deep Brain Stimulation Communication preference: Poster or oral presentation Key words: Deep brain stimulation – Trajectory planning – Automation Introduction: Accurate electrode placement is essential to achieve good clinical outcomes in subthalamic nucleus deep brain stimulation (STN-DBS) for people with Parkinson’s disease. Electrode trajectory planning is based on the visual assessment of manually planned electrode trajectories on magnetic resonance imaging (MRI) scans. To our knowledge, there is currently no algorithm available that can present an automatically planned and analysed trajectory for patients undergoing STN-DBS surgery. Our aim is to develop an algorithm that can plan a safe trajectory for a given target point faster than it would take to manually plan the trajectory. Method: The algorithm contains two parts: the selection of possible trajectories and trajectory analysis. The selection of possible trajectories is based on historical entry points (EPs) (n=231) corresponding to the T2-weighted MRI coordinate space. Historical EPs are transformed to patient-specific MRI space by a pipeline of image registration and point transformation using the ICBM 2009c nonlinear symmetric brain template. Historical EPs were first transformed to template space and after transformed to patient-specific MRI space. A cortical region of interest is defined based on the historical EPs. Samples are taken in the cortical region, and candidate EPs are adjusted to the patient’s anatomy. Four MRI features define an optimal trajectory (Fig.1): (1) T2-MRI voxel intensities, (2) contrast enhanced T1-MRI voxel intensities, (3) average distance to CSF, and (4) average T2-MRI voxel intensity along the first 7 mm from TP to EP. We hypothesize that an optimal trajectory maintains a safe margin relative to ventricles, sulci, blood vessels, and white matter hyperintensities by combining the first three features, while the fourth ensures maximal STN passage. Results: The total time to output a top 5 semi-automatically planned trajectories is about 8 minutes, including all MRI pre-processing and computational steps. Preliminary results showed that a DBS experienced neurosurgeon chose the semi-automatically planned trajectory over their manual planned one in 50% of the cases. Further improvements were integrated in the algorithm. These improvements will be validated by two neurosurgeons and results will be available at the ESSFN congress. Conclusion: We developed a novel semi-automatic algorithm by using historical surgical data, MRI-preprocessing steps and MRI analysis to obtain a set of potential trajectories for a new patient undergoing STN-DBS surgery. The algorithms output is obtained in a short timeframe which is suitable for clinical implementation. The algorithm offers a more standardized way of trajectory planning to guarantee safe patient-specific planning.

Introduction: Deep brain stimulation (DBS) is an effective therapy for the treatment of Parkinson's disease (PD). It improves the symptoms by stimulating the motor part of the subthalamic nucleus (STN). Traditionally, DBS surgery is performed using a stereotaxic frame, which allows high precision. However, it is often uncomfortable for the patients and makes the several hours surgery a big strain for them. The navigation-based, frameless NexFrame targeting system provides more tolerable surgical conditions for the patients. The strain can be further reduced if the operating time could be significantly shortened and only the minimum requiered number of test electrodes are used for the electrophysiological registration. Methods: Between October 2023 and February 2025, 6 patients underwent DBS implantation using a new surgical technique. During the procedure, bilateral electrodes were implanted simultaneously under real-time anatomical and electrophysiological control using a double NexFrame system and intraoperative 3D X-Ray (Siemens Pheno Artis). To assess the efficacy of the new technique, we determined the number of test electrodes used, duration of surgery, number of days in hospital and the reduction in levo-dopa dose and improvement in UPDRS III score six months after surgery. Results: An average of 3 test electrodes (1.5 per side) were used per patient (5 in the first case, 3 in three patients and 2 in two cases). The average duration of surgery was 3 hours 29 minutes, which included the time for two 3D X-Ray scans (10 minutes per scan) and the time for anaesthesia and draping between the two phases of surgery. For comparison, the conventional single-sided technique uses 3 test electrodes per side and the surgery takes on an average of 4 hours 58 minutes. The final electrodes were implanted in an average of 2 hours and 12 minutes. Patients were discharged from the department on the third ostoperative day. Levodopa requirement decreased from 960.16 mg to 553 mg, while UPDRS III improved from 40.16 to 19.5 points (51.44%). Dicussion: Based on our results, the simultaneous use of the double NexFrame system on both sides significantly reduces the operating time and the number of test electrodes required. Therefore it creates a safer, more comfortable and tolerable surgical situation for the patients and significantly improves the patients' symptoms.

Objectives: Responsive neurostimulation (RNS) targeting the centromedian (CM) thalamic nucleus has shown promising results for refractory epilepsy in both adult and pediatric populations. These treatment populations may have substantial differences in clinical presentation, but the relationship between these and variability in treatment response or programming strategies has not yet been addressed. Methods: We retrospectively reviewed 14 pediatric and 21 adult patients with refractory epilepsy, who underwent bilateral CM RNS implantation at Massachusetts General Hospital (MGH). Seizure burden was quantified using long episode (LE) counts, which represents presumed electrographic epileptiform activity lasting longer than 30 seconds, as detected by the device. Programming parameters were analyzed across programming epochs for up to 3 years post-stimulation initiation, using last observation carried forward (mean follow-up adults=1.7 years; peds=3.7 years). LE counts were Z-scored within periods of static detection settings in each patient. Baseline seizure burden was calculated as the average LE count over the first 21 days post-implantation. Relative reduction in seizure burden from baseline was calculated at 6, 12, 18, 24 months. Differences in relative reduction of Z-scored LE counts at each timepoint between pediatric and adult cohorts were assessed, using Welch's t-tests. Results: There was no significant difference in epilepsy syndrome distribution between pediatric and adult cohorts (FBTCS, GTC, JAE, JME, LGS/Dravet; p=0.84). However, developmental delay was more prevalent among pediatric patients compared to adults (86% vs 43%; p=0.03). Pediatric patients received higher charge density at 12 months post-stimulation initiation (2.0 uC/cm2 vs 1.2 uC/cm2; p<0.01) and had a greater relative reduction in LE counts in the first 6 months (46% vs 13%; p=0.13). Conclusion: Bilateral closed-loop stimulation of the CM region is an effective treatment option for both adult and pediatric patients with refractory epilepsy. Baseline clinical differences may influence treatment trajectories, underscoring the need for age-specific programming strategies to optimize clinical response. The significance of reduction in LE count may correlate with clinical improvement, but requires further investigation.

Over multiple studies, our team has expanded and refined our understanding of the basal temporal language area (BTLA) in patients with drug-resistant temporal lobe epilepsy. By integrating stereoelectroencephalography (SEEG) language mapping, lesion-symptom correlation techniques (e.g., voxel-based lesion-symptom mapping), and postoperative neuropsychological assessments, we have characterized how specific ventral temporal regions contribute to naming and memory functions. Our findings indicate that BTLA resection leads to a specific and early decline in naming, which, although partially transient, often remains below baseline levels over time. Similarly, postoperative verbal memory performance declines when the BTLA is involved in the surgical resection. Further, using cortico-cortical evoked potentials (CCEP), we revealed a robust and distributed basal temporal language network in the ventral temporal cortex supporting visual naming. Within this network, posterior ventral temporal regions behaved as “projectors,” whereas the fusiform gyrus functioned predominantly as an “integrator.” In contrast, for non-eloquent sites, the anterior fusiform gyrus demonstrated an opposite pattern, acting as a strong projector rather than an integrator. We also explored the surgical limits and localization of the BTLA in light of recent VLSM (voxel lesion-symptom mapping) studies, noting that maintaining a resection cavity anterior to the VLSM-defined critical region does not necessarily prevent postoperative naming decline. Lastly, our investigations extended to functionnectomes, enhancing our knowledge of BTLA connectivity and further emphasizing the importance of precise identification and preservation of language-critical regions to optimize postoperative outcomes.

Background: Deep brain stimulation of the anterior nucleus of thalamus (ANT-DBS) is a treatment option in refractory epilepsy, with a proven short and long -term efficacy. European registry -based data suggests significant differences in treatment outcomes. Different subregions of the ANT have been suggested as the most optimal targets, potentially explaining variable treatment outcomes. In addition to the existing histological data regarding the anatomical connections of ANT, a large number of white matter pathways have been described in humans using diffusion weighted imaging and tractography methods. Objective: Here we have studied the white matter pathways of different anterior thalamic nucleus subregions using probabilistic multi shell multi tissue (MSMT) constrained spherical deconvolution (CSD) tractography. Materials and methods: Thirteen healthy volunteers underwent MRI with T1 and DW images which were further processed for tractography using Mrtrix3 software. The centre, anterior, posterior and inferior aspects of the ANT were used as 2 mm spherical regions of interest (Roi) for fiber tracking. The location of responding (n=25; ≥ 50% seizure reduction) and non-responding contacts (n=37, <50% seizure reduction) in the stereotactic space from a group of 15 patients with ANT-DBS was compared to calculated fiber tracts. Results: Three main white matter pathways were identified in accordance with previous data: 1) inferior thalamic peduncle with fiber connections to amygdaloid complex; 2) anterior thalamic radiation with orbitofrontal, prefrontal and occasionally cingulate connections; and 3) posterior fiber pathway with terminations in the hippocampus, occipital cortex and parietal cortex. The connectivity pattern was similar in the anterior, centre and posterior ANT Rois, but the inferior part of ANT differed markedly with stronger connections to frontal cortical areas but with lesser connections to the inferior of posterior main fiber streams. The location of responding contacts matched with the fiber streams calculated from the anterior, centre and posterior aspects of the ANT while non-responding contacts located along the fiber stream between the inferior part of ANT and frontal cortical areas. Discussion: The differences in connectivity patterns of different ANT subregions together with existing outcome data suggest that the stimulation of all three main white matter pathways, namely inferior, anterior and posterior pathways is essential for optimal treatment outcomes.

Sleep spindles are oscillatory events specific to Non-Rapid Eye Movement (NREM) sleep, characterized by waxing and waning waveforms in the 10–16 Hz frequency range. They are generated in the thalamic reticular nucleus and propagated to other brain regions via thalamo-cortical circuits. Sleep spindles have been associated with cognitive functions and general intellectual ability. In addition to their role in physiological neural plasticity, spindles have also been linked to pathological off-line plasticity in both epileptic models and patients with epilepsy. Several studies suggest a connection between sleep spindles and interictal epileptic discharges (IEDs), which are considered markers of pathological neural plasticity in the central nervous system. We investigated the relationship between thalamic sleep spindles and thalamic IEDs in the anterior (ANT) and mediodorsal (MD) thalamic nuclei of epilepsy patients. Whole-night local field potentials (LFPs) from the ANT and MD were co-registered with scalp EEG/polysomnography using externalized leads in 15 pharmacoresistant, surgically non-treatable epilepsy patients undergoing deep brain stimulation protocols. DBS electrodes were localized in the ANT for 15 patients, and in the MD for 10 patients. Sleep spindles and IEDs were detected during all-night non-artifactual NREM sleep (stage 2 and 3). Both slow (~12 Hz) and fast (~14 Hz) sleep spindles were detected in the thalamic nuclei. Approximately 10% of the detected sleep spindles co-occurred with IEDs. These IED-associated spindles exhibited significantly longer durations and a broadband increase in thalamic and cortical activity, both below and above the spindle frequency range, compared to typical spindles. Additionally, the density of IEDs in the MD showed a positive correlation with the number of years since epilepsy onset. These findings suggest a role for the human ANT and MD in both physiological and pathological sleep spindle-related neural plasticity.

Objective: Drug-resistant epilepsy (DRE) remains a significant clinical challenge, with approximately 30% of patients failing to achieve seizure control with anti-seizure medications (ASMs). Deep brain stimulation of the anterior nucleus of the thalamus (ANT-DBS) has emerged as an effective neuromodulatory treatment for DRE, yet a subset of patients remains refractory, with only a small portion achieving seizure freedom. Cenobamate (CNB), a novel ASM with GABA-A receptor modulation and persistent sodium current inhibition, has demonstrated promising efficacy in seizure control even in ultra-resistant epilepsy. This study evaluates the potential synergy between cenobamate and ANT-DBS in patients with ultra-refractory focal epilepsy. Methods: A retrospective analysis was conducted on 44 patients who underwent ANT-DBS for drug-resistant focal epilepsy at Tampere University Hospital, Finland. Among these, 29 patients were initiated on cenobamate therapy, with 27 continuing treatment for a median follow-up time of 18 months. Treatment responses (≥50%-74% and 75%-99% seizure reduction and seizure freedom rates) were analyzed in the total cohort, as well as in the CNB and non-CNB subgroups. Safety and tolerability of cenobamate in ANT-DBS patients were also assessed. Results: Before cenobamate initiation, 61% of all included patients were responders to ANT-DBS, with only 7% achieving seizure freedom. Following cenobamate addition, seizure freedom rates significantly increased to 27% in the total cohort. The overall responder rate rose from 61% to 75%. In the CNB subgroup, the responder rate increased from 63% to 85%, with seizure freedom rates rising from 0% to 33%. Patients who were initial ANT-DBS responders exhibited the highest benefit, with 94% achieving seizure reduction and 47% reaching seizure freedom. In contrast, initial ANT-DBS non-responders had a lower response rate of 70%, with 10% achieving seizure freedom. In the non-CNB subgroup, both the responder and seizure freedom rates remained unchanged during the observation period. Discussion: The combination of cenobamate and ANT-DBS has the potential to significantly enhance seizure control in patients with ultra-refractory focal epilepsy. The observed synergy may be attributed to overlapping mechanisms involving GABAergic enhancement, sodium channel modulation, and network-level reorganization. These findings suggest that cenobamate is a promising adjunctive therapy in ANT-DBS patients, potentially increasing the likelihood of seizure freedom. Future prospective studies are warranted to validate these results and further explore the mechanistic interactions between cenobamate and ANT-DBS.

Background: Recent findings highlight the critical role of subcortical white matter tracts (WMTs) in supporting language processing. This report focuses on WMT monitoring using invasive stereo-electroencephalography (SEEG). We present two case studies: MN, a 17-year-old adolescent, and CO, a 10-year-old child, both with non-lesional, drug-resistant focal epilepsy originating from the left frontal lobe with rapid frontal propagation. Both patients underwent invasive intracranial monitoring to identify the epileptogenic zone and preserve eloquent functional areas. Electrodes were implanted along presumed dorsal language WMTs, as identified by preoperative MRI-DTI imaging. Method: A comprehensive language assessment battery was administered before, during, and after the monitoring procedure, evaluating naming, sentence repetition, comprehension and production of syntactically complex sentences, and reading of words and pseudowords. Results: MN demonstrated intact preoperative language functions. However, during SEEG monitoring, stimulation of electrodes located along the arcuate fasciculus (AF, figure 1 in the attached appendix) produced language interference resembling a phonological loop deficit, primarily manifested as sentence repetition failures. Stimulation of electrodes along the frontal aslant tract (FAT, figure 2 in the attached appendix) resulted in speech initiation difficulties (e.g., speech arrest or prolonged hesitations) and impaired production of syntactically complex sentences—particularly object-relative clauses. In contrast, CO exhibited preoperative language impairment. Nevertheless, monitoring of the AF using a word span repetition task was feasible. Importantly, in both cases, stimulation of electrode contacts placed outside the targeted tracts resulted in negative language mapping. Similarly, stimulation of electrodes not traversing known language pathways also yielded no interference. Conclusions: These cases underscore the value of subcortical language mapping using targeted language paradigms. Addressing tracts such as the AF and FAT enhances the precision of functional mapping, helping preserve critical cognitive functions—even in children with premorbid language difficulties—while optimizing surgical outcomes. Monitoring language in pediatric patients, particularly those with premorbid intellectual impairments, presents unique challenges. These are further complicated by the nature of SEEG, which does not fully cover the cortical surface but instead samples subcortical structures. Nevertheless, our findings demonstrate that stimulation along subcortical language tracts enables effective monitoring of both the tracts and their cortical terminations. This approach allows for indirect yet reliable identification of eloquent cortical language areas, offering a valuable tool for surgical planning when conventional surface-based mapping is limited. The full presentation will include video clips and imaging data illustrating the stimulated subcortical contacts and their spatial relationship to functional areas, providing a detailed visualization of the mapping process.